The study shows that among people who had survived a stroke, those with atrial fibrillation were 2.4 times more likely to develop dementia than those with normal heart rhythms.

“These results may help us identify potential treatments that could help delay or even prevent the onset of dementia,” says researcher Phyo Kyaw Myint, MD, of the University of East Anglia in Norfolk, U.K., in a news release. “Options could include more rigorous management of cardiovascular risk factors or of atrial fibrillation, particularly in stroke patients.”

Atrial fibrillation occurs when the heart's two upper chambers do not beat efficiently and results in an irregular heart rhythm. Researchers say about 15% of strokes occur in people with atrial fibrillation.

The risk of atrial fibrillation and dementia rises with age. Researchers say a growing number of studies have suggested that the two conditions might be linked.

Measuring Dementia Risk

In their study, published in Neurology, researchers reviewed 15 studies on the association between atrial fibrillation and dementia involving 46,637 participants with an average age of 72.

The results showed that atrial fibrillation was associated with double the overall risk of dementia among the participants.

But when they looked at the results more closely, researchers found this relationship was only significant in the seven studies that involved stroke survivors. In these studies, about 25% of stroke survivors with atrial fibrillation developed dementia and the risk of dementia was 2.4 times higher among those with this heart condition.

Researchers say the results suggest there is consistent evidence to support a link between atrial fibrillation and increased dementia risk among stroke survivors, but it's still unclear whether these two conditions are linked in the general population.